wjpmr, 2019,5(8), 247-250 SJIF Impact Factor: 4.639 WORLD JOURNAL OF PHARMACEUTICAL Review Article Nagrath et al. AND MEDICAL WorldRESEARCH Journal of Pharmaceutical and Medical ResearchISSN 2455 -3301 www.wjpmr.com WJPMR ANATOMY OF THE PELVIC FLOOR AND ANAL SPHINCTERS: A REVIEW ARTICLE Dr. Anurag Nagrath*1, Dr. Amandeep Kaur2, Dr. Subash Upadhyay3 and Dr. J. Manohar4 1PG Scholar Deptt. of Rachana Sharir. 2PG Scholar Deptt. of Dravya Guna. 3HOD & Professor Deptt. of Rachana Sharir. 4Associate Professor Deptt. of Rachana Sharir Sriganganagar College of Ayurvedic Science & Hospital, Tantia University, Sriganganagar – 335001, India. *Corresponding Author: Dr. Anurag Nagrath PG Scholar Deptt. of Rachana Sharir. Article Received on 22/06/2019 Article Revised on 12/07/2019 Article Accepted on 02/08/2019 ABSTRACT The pelvic floor is a striated muscular structure providing enclosure to the bladder, uterus, and rectum. It plays significant role in storage and evacuation of urine and stool. This article reviews the anatomy of the anal sphincters and the pelvic ûoor. The internal and external anal sphincters are responsible for maintaining faecal continence at rest and when continence is threatened, respectively. Defecation is a somato-visceral reûex regulated by dual nerve supply (i.e. somatic and autonomic) to the anorectum. The net effects of sympathetic and cholinergic stimulation are to increase and reduce anal resting pressure, respectively. Faecal incontinence and functional defecatory disorders may result from structural changes and/or functional disturbances in the mechanisms of faecal continence and defecation. KEYWORDS: The pelvic floor is anorectum. INTRODUCTION The deep muscles also known as the levator ani muscle originate from the pectinate line of pubic bone and the Pelvic floor is a funnel or dome-shaped muscular sheet fascia of obturator internus muscle and are inserted into made up of striated muscle which is placed such that it coccyx. Holl a German anatomist first described that encloses and supports the urinary bladder, uterus and some pubococcygeus muscle fibers looped around rectum along its midline hiatuses. Pelvic diaphragm rectum and formed “puborectalis” or “sphincter recti”. forms the inferior boundary of abdominopelvic cavity Together pubococcygeus, puborectalis and puboperineal extending from pubic symphysis anteriorly to coccyx muscles are collectively called “pubovisceralis muscle”. posteriorly and between two pelvic sidewalls. It is Lawson described insertions of pubovisceralis muscle responsible for storing and voiding of urine and feces into urethra, vagina, perineal body and anal canal. He through somatovisceral reflexes. named them pubourethralis, pubovaginalis, puboperinealis and puboanalis respectively and they Anatomy basically provided support to visceral organs. Pelvic floor Pelvic floor is made up of a number of muscles, which Rectum are further organized in superficial and deep parts. Even The rectum is continuation of sigmoid colon at the level though controversy exists as regarding the nomenclature, of third sacral vertebra upto the upper end of anal canal. the superficial muscles include external anal sphincter, At the beginning rectum is of similar caliber as sigmoid perineal body and transverse perinea muscles. The deep colon, while its lower part is dilated as rectal ampulla. pelvic floor muscles (anatomic pelvic floor) include four Rectum is devoid of sacculations, appendices epiploicae major muscles namely pubococcygeus, ileococcygeus, or mesentery. The taenia blend about 5 cm above ischiococcygeus and puborectalis. Caudal extension of rectosigmoid junction, descend as broad wide bands on the circular layer of smooth muscle of rectum into anal anterior and posterior walls of rectum, fuse to form canal forms the internal anal sphincter (IAS) and the continuous encircling layer of longitudinal muscle along extension of longitudinal layer of smooth muscle of the entire length of rectum. Anteriorly few muscle fibers rectum forms the external anal sphincter (EAS) of the pass forwards to perineal body as musculus recto- anal canal. urethralis. Two facsimile of smooth muscle may pass from front of second and third coccygeal vertebra to www.wjpmr.com 247 Nagrath et al. World Journal of Pharmaceutical and Medical Research blend with posterior part of rectal longitudinal muscle region has rich arterial and venous plexus and plenty of forming rectococcygeal muscles. connective tissue. The junction between columnar and squamous epithelium is the anal transition zone (ATZ) Upper and lower rectum are separated by a horizontal which is of variable length and position. Submucosa of fold consisting of mucosa, circular muscle and part of ATZ is rich in nerve endings including thermoreceptors. longitudinal muscle, marked externally by an They play a role in continence by providing a highly indentation. Upper rectum is derived from the specialized „sampling‟ mechanism by which the contents embryological hind gut, it is surrounded by mesorectum of lower rectum are identified during periods when upper and its contents namely superior rectal artery and its anal canal relaxes to allow rectal contents to come into branches, superior rectal vein and tributaries, lymphatic contact with upper anal canal epithelium. Anal canal is vessels and nodes along superior rectal artery, branches surrounded by internal and external anal sphincters. from inferior mesenteric plexus to innervate rectum and loose adipose connective tissue down to the level of (Internal anal sphincter is a well defined ring of levator ani (pelvic floor). Mesorectum is enclosed by obliquely oriented smooth muscle fibers continuous with mesorectal fascia which is derived from the visceral the circular muscle of the rectum and terminating at the peritoneum, and is also known as visceral fascia of junction of superficial and subcutaneous parts of EAS. mesorectum, fascia propria of rectum or presacral wing Fibers from conjoint longitudinal coat cross the lower of hypogastric sheath. Upper rectum generally contains parts of the IAS. Interstitial cells of Cajal (ICC) are feces and can distend towards the peritoneal cavity. The located along the periphery of muscle bundles within the lower part of rectum is derived from cloaca, is circular layer. External anal sphincter is a tube shaped surrounded by condensation of extra peritoneal sphincter of striated muscle (Type I, slow twitch fibers) connective tissue and is generally empty except during for prolonged contracion which has deep, superficial and defecation. Number of enteric ganglion are much less in subcutaneous parts, now considered to be as a single rectum and even lesser in anal canal as compared to rest functional and anatomical entity. Upper most fibers of the colon. Interstitial cells of cajal (ICC) are seen as (deep part) blend with fibers of puborectalis, anteriorly dense network along submucosal and myenteric borders decussate with superficial transverse perinei muscle and in rectum. posteriorly some fibers attach to anococcygeal raphe. Middle fibers (superficial) mainly surround the lower Anal Canal part of internal anal sphincter, attach anteriorly to Anal canal is more like an anteroposterior slit around 2.5 perineal body and posteriorly to anococcygeal raphe cm to 5 cm long. Anatomically or embryologically the through decussation of some of its fibers anteriorly and anal canal is shorter while surgically it is assumed to be posteriorly. Lower fibers (subcutaneous) lie below the longer. Proximal end of anatomical anal canal is marked level of internal anal sphincter. by anal valves and surgical or clinical by distal end of ampullary part of rectum. Upper part of anal canal Nerve Supply To The Pelvic Floor (proximal 10 mm) is lined by columnar epithelium The anal canal, rectum and pelvic floor are supplied by similar to rectum. Subepithelial tissues here have profuse sympathetic, parasympathetic and somatic fibers. submucosal arterial and venous plexus. Terminal Sympathetic preganglionic fibers originate from lower branches of superior rectal vessels pass downwards three thoracic and upper two lumbar spinal segments, towards anal columns. Submucosal veins drain into synapse in the ganglia associated with lumbar and sacral submucosal rectal venous plexus and also through upper sympathetic trunk in the aortic, superior and inferior internal anal sphincter into intermuscular venous plexus. hypogastric plexus. Preganglionic parasympathetic Each anal column contains a terminal radicle of the fibers arise from neurons of second to fourth sacral superior rectal artery and vein, these vessels being spinal segments. Superior hypogastric plexus lies largest in left lateral, right posterior and right anterior anterior to aortic bifurcation and sacral promontory, quadrants of wall of anal canal and the sub epithelial between the two common iliac arteries. It provides tissues here expand to form three “anal cushions” which branches to uteric/ testicular plexus, divides into right seal the anal canal and help in maintaining continence to and left hypogastric nerves. Hypogastric nerves join flatus and fluid. They also have a role in formation of preganglionic fibers from ventral rami of second, third hemorrhoids. Mid anal canal (next 15 mm) including the and fourth sacral nerves to form inferior hypogastric anal columns and anal valves at their lower end are lined plexus, lying posterior to urinary bladder in the thin by stratified or a modified columnar epithelium. Mucosal extraperitoneal connective